Employment
July 2024 - present
Postdoctoral Fellow
National Centre For Radio Astrophysics - Tata Institute Of Fundamental Research (NCRA-TIFR)
Pune, India
December 2023-June 2024
Postdoctoral Fellow
Manipal Centre for Natural Sciences (MCNS), Manipal, India
April 2022-October 2023
Project Associate
Aryabhatta Research Institute of observational sciencES (ARIES), Nainital, India
March 2020-July 2021
Senior Research Fellow (SRF)
Aryabhatta Research Institute of observational sciencES (ARIES), Nainital, India
March 2018- February 2020
Junior Research Fellow (JRF)
Aryabhatta Research Institute of observational sciencES (ARIES), Nainital, India
Education
2018-2023
Ph.D. in Astrophysics
Aryabhatta Research Institute of observational sciencES (ARIES), Nainital, India
Thesis title: Investigating the Nature and Structure of the Inner Regions in Active Galactic Nuclei. Supervised by:
Dr. Hum Chand and co-supervised by Prof. Shantanu Rastogi . Thesis submitted to: Deen Dayal Upadhyaya Gorakhpur University, Gorakhpur, India.(submitted in September 2023 and awarded in February 2024).
2015-2017
Master of Science (M Sc.) in Physics
Banaras Hindu University
I specialized in space physics. The cumulative grade point average (CGPA) was 7.3. The final year dissertation was titled: Study of properties of CsI as a suitable photocathode for UV astronomy purposes .The dissertation work was a part of this publication and it was presented at a national conference, subsequently published in the proceedings.
2011-2014
Bachelor of Science (B Sc.) with honors in Physics.
Deshbandhu College, University of Delhi
I graduated with an honors in Physics with an aggregate percentage of 68.69%.
Technical Skills
Computer Skills
I am fluent in the usage of Python language for the general programming purposes. I use astropy affiliated packages like CCDPROC and PHOTUTILS for the optical data reduction procedures. I have experience handling large volume of data obtained from the ARIES telescopes. As part of the data archive team, I have developed software for effective data management and pipelines in Python to homogenise the data and perform automatic photometry. For my research, I use the mcmc based code JAVELIN extensively.
Besides JAVELIN, I have used ICCF, DCF etc. for cross correlation analysis. I have been implementing Jupyter-notebooks for most of the projects as
I feel the notebook-based implementation is the most transparent and easy way for codes to work.
I use GitHub for keeping the codes together and as a version control system for my projects. Besides Python based packages,
I have used IDL language in the past and have some experience programming with FORTRAN as well. I have basic knowledge of the HTML/CSS language and currently maintain a couple of static websites.
Language Skills
I use English, Hindi and Maithili as languages for communication. Maithili is my mother tongue, Hindi was learnt as I have spent almost my entire life in Hindi-speaking regions of India and English
has been taught as a medium of instruction ever since I went to school. As a result, English is my primary language for all formal communications. Besides there three, I can read and write Bangla/Assamese due to my fondness for the script.
Telescope experience
I have observed using the telescopes located at ARIES, namely, the 1.04m ST , 1.3m DFOT and 3.6m DOT .
Besides these telescopes, I have observed remotely using the network of Thai Robotic Telescopes (TRT) located in USA, Australia, Thailand and China. I have experience reducing and analysing the data obtained from these teelscopes. We are developing an aperture photometry
pipeline, written purely in PYTHON. The details can be found here. . Following is a list of competitive telescope time awarded for the various proposals:
GROWTH India Telescpe (GIT) Accretion disk reverberation mapping of AGN using the GROWTH telescope GROWTH-ADRM , (cycle 2022-C1) as Co-I
Devasthal Optical Telescope (DOT). In search of luminous Quasars at the cosmic dawn , cycle: 2020-C2 (Oct-2020:Jan-2021), as PI.
Thai Robotic Telescope (TRT). Photometric reverberation mapping of the accretion
disk in AGN , cycles: 8A (Oct-Dec:2020), 7D (Jul-Sep:2020) and 7C (Apr-Jun:2020)
as PI.
Devasthal Fast Optical telescope (DFOT). Photometric Reverberation Mapping of central region of AGN using H-beta emission line , cycles: 2019 (A), 2019
(B) and 2020 (A), as PI
Sampoornanand telescope (ST). Multi-wavelength photometric observations of a few Low Red-Shift Broad Line Seyfert 1 Galaxies , cycles: 2018 (B), 2019
(A) and 2020 (A), as PI
Very Large Telescope-European Southern Observatory (VLT-ESO). Dissecting baryon cycle in overdense environments , cycle: P106 as Co-I.
PI: Ravi Joshi
Awards/Fellowships
2018-2021
Research Fellowship (JRF/SRF)
Fellowship awarded for 3 years (2 years as JRF + 1 year as SRF) by the Department of Science and Technology (DST), an arm of the Ministry of Science and Technology, Govt. of India.
2017
Qualified JEST-2017
Joint Entrance Screening Test
Entrance exam for admission to Ph.D. in Physics at premier research institutes in India.
2016-17
ISRO-SSPS fellowship
Indian Space Research Organization (ISRO)
Competitive fellowship awarded by ISRO to the final year M.Sc students for promoting space science research in India.
Other Activities
I was event Chair for the Young Astronomers' Meet (YAM)-2022 ; a conference which brought together about 160 Ph.D students working in astronomy across the country. In 2021, we founded a web portal named CosmicVarta , a platform to present simplified versions of research articles in astrophysics to the general public. I was responsible for managing the website until October 2022, and edit articles received from researchers across the country regularly. Besides, I have actively participated in various outreach activities at my institute, some of which include the ARIES National Science Day celebration , held on the 28th of February 2021, and the ARIES e-lecture series , which took place during the COVID-19 lockdown in the months of May and June 2020.
Research
Research
My current research focuses on the properties of the most luminous objects in the known universe yet:
Active Galactic Nuclei (AGN) . We use various techniques backed by observational data in X-ray, UV, Optical and radio wavelengths to understand the behaviour of matter in the close proximate regions of the Supermassive Black Holes residing at the centre of these objects. See this video for a very helpful animation zooming into the inner regions of quasars. I also prepared a curated list of review papers on AGN during my PhD. Prospective students or even experts for that matter, might find this collection useful! Ongoing projects: Resolving the accretion disk structure in AGN: As the innermost regions of AGN are too difficult to resolve spatially, a technique known as *Reverberation Mapping* is used to resolve these innermost regions. As the light travels from the inner to our regions, the fluctuations in the two regions can be recorded, with a lag understood as the light travel time. This technique yields the size of the accretion disk.Understanding the dynamics of gas in the broad line region (BLR) of AGN: We don't know what is the structure and the dynamics of gas in the BLR. To understand the dynamics of matter in these regions, we use emission line diagnostics as a tool. The various emission lines (Hα, Hβ, MgII, CIV etc. ) originating from these regions can be resolved using ground-based spectroscopic measurements, which provide clues to the structure and dynamics of matter in these regions.Microvariability studies for a handful of interesting AGN: AGN are known to be variable at all time scales. We exploit this method to relate the exciting phenomenon observed in different wavelengths such as weak emission lines, radio jets and the γ- ray emission, with the microvariability observed in these AGNs.Photometric Reverberation Mapping: we use the technique of Photometric reverberation mapping using narrow band filters to extract the size and extent of the BLR in AGNs. This method is quite efficient at getting the sizes with a fraction of the telescope time needed for the traditional reverberation mapping campaigns.Variability and its connection with Physical parameters : We study AGN flux variability using optical light curves from the Zwicky Transient Facility (ZTF) survey. In order to explore the correlations between the variability parameters and the physical properties of the AGN, such as black hole mass, X-ray luminosity, bolometric luminosity, Eddington ratio, R-feII, and redshift, we model the light curves. Our study demonstrates the potential of using large-scale optical surveys to study the diverse nature of AGN.Physical properties of very high redshift (z> 5) quasars:
High redshift quasars, being the most luminous non-transient objects, hold the keys to the understanding of the universe during and immediately after the epoch of cosmic re-ionization Using a subset of IR bright quasars, we look for the quasar properties including the SMBH mass using the CIV and MgII emission lines arising out of the Broad-line region of these quasars.Published work:
In this work, we have studied the Hβ emission line profiles in a peculiar class of Seyfert galaxies: the Narrow Line Seyferts. Using a combination of 11 physical parameters, we have studied the behaviour of a sample of around 150 NLSy1 galaxies as compared to the general Broad Line Seyfert population and discovered that peculiar behaviour of NLSy1 galaxies holds true for a large sample.
AGN are known to be variable at all time scales. In this project, we use a handful of peculiar Narrow Line Seyfert 1 (NLSy1) Galaxies, and checked for the variability at smallest time scales. We relate the phenomenon of γ ray emission jet with the microvariability observed in this sample of AGN and find out that these AGNs behave like blazars at shorter time scales of variability.
As the innermost regions of AGN are too difficult to resolve spatially, we use a technique known as Reverberation Mapping to resolve these innermost regions. As the light travels from the inner to our regions, the fluctuations in the two regions can be recorded, with a lag which is understood as the light travel time. This technique yields the size of the accretion disk. In this work we have used this technique to measure the accretion dize sizes for 19 AGNs selected from the ZTF survey.
Photometric Reverberation mapping is a cost-effective alternative to traditional reverberation mapping. However, the technique has not been used for a large sample of quasars so far. In this work, we have calibrated the technique of PRM with the traditional RM and also performed simulations to devise an optimum strategy for a successful PRM campaign.
. In this study, we present initial results from our accretion disk reverberation mapping campaign targeting AGN with Super High Eddington
Accreting Black Holes (SEAMBH). Our analysis on one of the sources- IRAS 04416+1215;
based on the broadband observations using the Growth India telescope (GIT), reveals that the
size of the accretion disk for this source, calculated by cross-correlating the continuum light
curves is larger than expected from the theoretical model.
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Travel
Travel articles
Born with an innate desire to travel around the world, I consider myself lucky to be in a profession where I can travel a lot both for work and fun.
At the moment, my travel diary is filled with a few places in India coupled with a visit to China but with time I aim to travel to all the 7 continents on the planet. Some recent travel blog posts are posted below.
I traveled to Kerala in October 2018 only to be left mesmerized by the beauty, culture and the cleanliness of the part of my country rightly known as the 'God's own country'. This article is my version of the experience I had in approximately a week that I spent in Kerala.
China as a place, has always fascinated me since childhood! This article is about my maiden trip to China, which resulted due to an international conference held in Guilin, Guanxi province.
Not too many people have Nagaland in their bucket list. Uncomfortable roads, poor transport system and a lot of corruption are a few factors which contribute to it. Added to it the stories of a still very active insurgency, Nagaland although an extremely beautiful hill state doesn't manage to attract a lot of tourists.
I traveled to Nagaland and of course, will definitely want to visit again!
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Blog
My Blog
Sometimes few random things cross my mind and get structured​ in the form of sometimes little, sometimes eerily long blog posts. Currently, my blog is live on medium. A few posts are avilable below.
Two books by Sanjeev Sanyal, a noted economist: 'Ocean of Churn' and 'The land of the seven rivers' offer a very different perspective on the history of ancient India, in a manner untold before. Both of the books offer a very interesting journey through the geography of India and its surrounding lands and the ocean. I present a brief review of both the book simultaneously.
A personal account of the lockdown implemented to counter spread of the ongoing COVID-19 disease.
The radio has seen a rapid change thanks to the internet broadcast. With 100,000+ channels available to listen for free, is it a watershed moment for the world of radio entertainment? In this article, I put my thoughts regarding the resurgence of radio in the internet era and how to enthrall ourselves with the exciting world of radio.
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